This invention relates to central air conditioning with multi zone controllers for serving separate comfort air spaces, it being a general object of this invention to independently control air temperature and air quality. Air is conditioned herein by the controlled application of chilled and/or hot water, however it is to be understood that mechanical refrigeration and gas fired or electric furnaces can be employed. Air quality is conditioned herein by the controlled filtration of return air (RA), an advantageous feature of this system being bypass of excess supply air through run-around ducting, in response to closure of one or more zone dampers, and characterized by a bypass damper means that prevents excess supply air pressure, it being an object of this invention to provide a bypass filtration module that replaced the prior art bypass and in the form of a unit that is installed in the run-around ducting. A feature of this bypass filtration module is its coordinated functions in response to zone controller closures as well as air quality deterioration in any one or more of the separate comfort air spaces serviced by this system.
It is an object of this invention to combine variable air volume (VAV) and a bypass filtration system (BPFS), operable with a multiplicity of zone controllers and each of which services a separate conditioned zone. The zone controller draws air from a continuously operating central air conditioning unit, a cooling and heating unit that receives outside air (OSA) and return air (RA) and which delivers supply air (SA) at substantially constant volume and at a controlled temperature, and at a controlled pressure by means of a recirculation duct in which the bypass-filtration module is installed for air quality and temperature control. The zone controllers discharge conditioned supply air on demand in response to thermostat controls in each separate zone, the central air conditioning unit being activated when there is a demand, and any surplus conditioned air is recirculated through the bypass-filtration module herein disclosed. In accordance with this invention, the bypass-filtration module is comprised of parallel ducting and each controlled by a positionable air flow restrictor means, one of which responds to return air pressure, and one of which responds to an air quality sensor (AQS). In practice, there is a pressure sensor at the delivery of the central air conditioning unit, and there is at least one air quality sensor in a conditioned or related zone and preferably in the return air (RA) duct as shown herein. Accordingly, it is an object of this invention to coordinate both the supply of tempered air (heated or cooled) and the quality thereof.
Distribution of air tempered by the central air conditioning unit is by zone damper means in each of the zone controllers, the volume of supply air discharged being governed by a thermostat in the separate zone served by said controllers. As the conditioned air demand decreases, supply air flow is restricted so as to cause pressure to increase in the supply air duct and which is sensed and a signal transmitted to a bypass air flow restrictor means of the bypass-filtration module, for recirculating a commensurate air volume while meeting air flow demand from the supply air duct. The air flow restrictor means is a variably positionable motorized damper.
Quality of air is determined to exist by any one of a number of contaminant-gas sensors. That is, particulate matter and/or gasses such as carbon dioxide are detected and their proportionate density determined. And, when a certain threshold of density of a contaminant is determined, the air quality sensor (AQS) responds and a signal is transmitted to the filtration air flow restrictor means of the bypass-filtration module, for processing a recirculated air volume commensurate with the demand signal. It is an object therefore, to provide filter means in the bypass-filtration module, a means for removing particulate matter and/or means for removing certain contaminant gasses. In practice, filter packs of varied mesh are employed, and carbon filter packs or the like to remove certain gasses.